What it is
VIP (vasoactive intestinal peptide) is a 28-amino-acid neuropeptide with broad anti-inflammatory and immunomodulatory roles, meaning it helps regulate immune activity. It is studied, often intranasally, in the context of chronic inflammatory response syndrome (CIRS) and pulmonary conditions.
In the PeptidesAI encyclopedia it is categorized under both healing and immune. A pharmaceutical form of VIP, aviptadil, has been tested in clinical trials for COVID-19 respiratory failure.
How it's thought to work
VIP activates VPAC1 and VPAC2 receptors, promoting vasodilation (widening of blood vessels), downregulating pro-inflammatory cytokines and shifting immune responses toward a regulatory, anti-inflammatory profile. A review of the VIP and PACAP system describes inhibition of pro-inflammatory cytokines and chemokines and enhancement of anti-inflammatory factors, mediated through the VPAC1, VPAC2 and PAC1 receptors.
What the research says
Preclinical and small clinical work supports anti-inflammatory effects. Its best-known structured use is as one step of the Shoemaker protocol, a multi-step treatment approach for CIRS. A 2024 literature review of CIRS treatment lists the supporting VIP studies as case series and open-label trials rather than randomized trials. In a randomized trial of intravenous aviptadil in COVID-19 respiratory failure (TESICO), the independent monitoring board recommended stopping the aviptadil comparison for futility. VIP is not FDA-approved for these uses.
Reported side effects
Reported effects include flushing, a drop in blood pressure, lightheadedness, and nasal irritation with intranasal use.
Reconstitution
VIP is supplied as a lyophilized (freeze-dried) powder, commonly in 5 mg and 10 mg vials. The PeptidesAI encyclopedia notes that it is also prepared as a nasal spray solution rather than only injected. The amount of peptide in the vial is fixed; the water added only changes how concentrated the solution is.
Worked example. A 5 mg vial is 5,000 mcg. Reconstituted with 2 mL of BAC water, that works out to 5,000 mcg ÷ 2 mL = 2,500 mcg/mL. On a U-100 insulin syringe, where each unit is 0.01 mL, each unit holds 2,500 × 0.01 = 25 mcg. Use the peptide reconstitution calculator to work out the concentration and units for any vial size and water volume.
Important notes
VIP can lower blood pressure. It is not FDA-approved for the uses described.
Sources
- VIP-PACAP system in immunity: new insights for multitarget therapy.. Gomariz RP et al. Annals of the New York Academy of Sciences, 2006. Review
- Chronic inflammatory response syndrome: a review of the evidence of clinical efficacy of treatment.. Dooley M et al. Annals of Medicine and Surgery, 2024. Review
- Intravenous aviptadil and remdesivir for treatment of COVID-19-associated hypoxaemic respiratory failure in the USA (TESICO): a randomised, placebo-controlled trial.. Brown SM et al. The Lancet Respiratory Medicine, 2023. Human trial
Frequently asked questions
These questions cover the same ground as the sections above, in a shorter format.
What is VIP?
Vasoactive intestinal peptide, a 28-amino-acid neuropeptide with anti-inflammatory and immunomodulatory roles, studied in CIRS and lung conditions.
How is VIP thought to work?
It activates VPAC1 and VPAC2 receptors, promoting vasodilation, lowering pro-inflammatory cytokines and shifting immune responses toward a regulatory profile.
What does the research on VIP say?
Preclinical and small clinical work supports anti-inflammatory effects, but the CIRS studies are case series and open-label trials, and a randomized aviptadil trial in COVID-19 was stopped for futility.
What are the reported side effects of VIP?
Flushing, lower blood pressure, lightheadedness and, with intranasal use, nasal irritation.
How much is one unit from a 5 mg VIP vial?
With 2 mL of BAC water, a 5 mg vial is 2,500 mcg/mL, so one unit on a U-100 syringe (0.01 mL) holds 25 mcg.
The full entry, plus the calculator
The PeptidesAI app has the complete encyclopedia entry for VIP — one of 70 compounds covered — plus the reconstitution calculator, a dose log and reminders. Free to download on iPhone.
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